The present invention relates to television processing apparatus and methods. More particularly, the present invention relates to a television multiple frame store having a cyclical repeat capability and may include the ability to write protect one or more selected frames of the cyclical sequence.
Frame store memory systems for television picture images are known in the prior art. Such devices include video tape recorders, disk recorders and solid state memory arrays.
In some specific applications a hitherto unsolved need has arisen for a television frame store which is controlled in a manner which provides unbroken cyclical repetition of a selectable segment of picture frames and which may further include the capability for write protecting one or more single frames of the segment.
One such application has arisen in the medical field. A treatment for heart disease, known an angioplasty, involves the insertion of a catheter into the blood stream of the patient. The catheter is moved to the heart region. A radiopaque dye is released into the bloodstream and x-ray excited television images are produced. These images provide the data necessary to enable the treating physician to locate and treat occluded arteries and veins in the vicinity of the heart.
The dispersal of the radiopaque dye, once released, is quite rapid; and, only a small segment of the television picture images (frames) are relevant to locate the blocked blood vessel or blood vessels in need of treatment. In fact, a single cycle of the heart following release and local dispersal of the dye is sufficient. Because of the ephemeral nature of the x-ray images due to rapid dispersal and dilution of the dye throughout the bloodstream, the initial moments following release of the dye have been routinely recorded, usually with the aid of a helical scan video tape recorder. Such machines have the capability of "freeze frame" and slow motion playback, and have been used to provide selected single images of the procedure. Several drawbacks attend this prior art approach. First, the video tape recorders typically store only a single field (256 horizontal scanning lines or one half the frame image) in a single helical scan. Thus, when that helix is scanned in place in order to display a still image, only one half of the picture is reproduced. Thus, only one half of the available resolution is presented on the display which presents a severe handicap to the treating physician.
A further drawback of the prior art is that when a single image is displayed as a still image over and over, the noise pattern for that selected image is also repeated in place over and over. This noise, which is filtered out during real time by the observer's mental perception process, becomes very apparent and constitutes a further major distraction and reduction of resolution in the picture.
It has been discovered by the inventors that if a selected, relatively short segment of consecutive picture frames is repeated without delay at the real time image scanning rate, the problems which noise are eliminated and the subject matter is much more perceptible and useful to the observer.
While positionable head disk drive memories have the capability to store picture frame sequences, the time required to move the head back to the beginning of the segment practically prevents uninterrupted repetition of the multiple frame sequence. Solid state multiple frame memories are not subject to this delay.
In the television broadcast field a hitherto unsolved need has arisen for a video delay loop of relatively short duration, such as one second. This need is particularly keen in live television programming where it may be necessary to delete expletives and other unanticipated events and to replace live action with a still image during the duration of the unacceptable portion of the live program. While it is known to provide a still frame image in the event that the television signal is lost, that technique still did not provide a preview delay to enable an operator to switch to a still frame manually as a matter of human judgment.
In the design and analysis of industrial processes a hitherto unsolved need has arisen for an analytical tool for presenting an unbroken cyclically repeating sequence of images of process operation in order to understand better the process in question and to develop and improve the process being observed.